It would have been daunting for the most experienced cabinet minister. But Jacqui Smith didn't have the luxury of even a full day in her new department before being thrown into a potential crisis.

Less than 24 hours after becoming the first female home secretary she was woken in the early hours to be informed of the bomb. She then held talks with police and security experts at her department, chaired a meeting of the government's emergency committee, spoke to the main opposition party spokesmen, briefed the cabinet and the prime minister before giving two statements to the media.

She also announced the appointment of Admiral Sir Alan West, a former first sea lord, as a junior security minister.

"We are currently facing the most severe and sustained threat to our security from international terrorism," Ms Smith said in Downing Street.

Not that she would have been entirely on her own as events unfolded. Sir David Normington, permanent secretary at the Home Office, was involved in briefing her as was Sir Gus O'Donnell, the Cabinet secretary.

Gordon Brown made a few comments about the situation on a visit to a school in the morning but left the important statements to Ms Smith. Observers detected a change of tone, away from some of the more dramatic responses to terror alerts from former home secretary John Reid.

When asked about the bomb during a radio interview yesterday morning, Jack Straw, also a former home secretary, said the discovery was "very saddening" but "these things happen".

At 10am Ms Smith chaired a meeting of Cobra, the emergency response committee, at the Cabinet Office, attended by senior members of the security services and police officers including Deputy Assistant Commissioner Peter Clarke, head of counter-terrorism at Scotland Yard. The meeting lasted 50 minutes.

Shortly afterwards she briefed the cabinet at a meeting which was arranged to discuss constitutional reform. She and Sir Alan then gave Mr Brown more details in a private session.

On a visit to a children's centre in north-west London, Mr Brown said: "The first duty of the government is the security of the people and as the police and security services have said on so many occasions we face a serious and continuous threat to our country." Ms Smith then briefed the shadow home secretary David Davis and Liberal Democrat spokesman Nick Clegg on the operation. They did not discuss the prospect of further anti-terrorism legislation. Opposition leaders David Cameron and Sir Menzies Campbell offered support for the government's position. "This is a time for parties to work together to make sure we make our country as safe as possible," Mr Cameron said. Conservative MP Patrick Mercer, sacked by Mr Cameron as security spokesman, said: "This is a time that we always knew was going to be tense - the end of the Blair era and the start of the Brown era."

The new security supremos

Admiral Sir Alan West, pictured below, the former head of the navy and surprise appointment as minister for security, is known for his straight talking, notably in his role as first sea lord where he lamented the decline in the number of ships in his fleet.

His appointment, along with that of Lord Stevens as adviser on international security, is likely to ensure that the fight against terrorism will take on a high profile under the new administration.

Whether that profile, in the task of inspiring public confidence, will turn out to be too high for the liking of Scotland Yard and Britain's three security and intelligence agencies - MI5, MI6, and GCHQ - remains to be seen.

Sir Alan was typically forthright last year when asked his view about military action against Iran. "The impact would be absolutely horrendous," he replied. "Getting involved in military action would be a very silly thing to do." Lord Stevens, 64, brings more than 40 years experience in the police to his new role. He was commissioner of the Metropolitan police between 2000 and 2005, a post he took over after being chief. He also chaired the inquiries in Northern Ireland into the alleged collaboration between the security services and paramilitary groups.